Acting Homeland Security Secretary Chad Wolf traveled to a recently completed section of barriers in Yuma, Arizona, to make the announcement.
"Today is a milestone that’s been reached and a celebration is in order," Wolf said, adding "We have built more walls in three years of this administration than the entire eight years of the last administration."
Trump has repeatedly pledged to construct 450 miles of barriers by the end of 2020 -- but most of the 100 miles completed thus far have been replacements of the smaller barrier designs that were constructed with decades-old technology.
The U.S.-Mexico border is more than 1,950 miles long.
Construction is underway -- but not yet completed -- in certain areas where barriers did not previously exist, including the Rio Grande Valley in southern Texas. Over the past year Department of Homeland Security officials have waived several environmental laws -- including the Clean Water Act and Endangered Species Act -- to make way for wall construction.
A federal appeals court released $3.6 billion in border wall funding on Thursday pending further legal action. A lower court in El Paso, Texas had temporarily blocked the funds before the injunction was lifted.
Wolf said the month-long delay could impact the DHS' ability to deliver on the remaining stretch of barriers.
"But I can tell you right now that we remain confident that we are on track for 400-450 miles that are either completed or under construction by the end of 2020," Wolf said.
Customs and Border Protection has referred to the new wall system as "replacements," but Wolf insisted on Friday that all 100 miles should be considered "new wall systems" because access roads, surveillance and lighting were also built along with the barriers.
Mexico has refused to fund any of the administration’s border barrier projects, despite Trump’s 2016 campaign promise that U.S. taxpayers would not foot the bill.
Congress approved $1.4 billion in December for border wall construction as part of the 2020 budget. It was the same funding level agreed to last year after the stalemate over the budget resulted in the longest government shutdown in U.S. history. The Congressionally approved funds fell short of the Presidents initial demand of $5 billion for border wall construction.